Scissors of the type described above are known from U.S. Pat. No. 4,223,439 to Rommel. The outer toothing of the movable cutting jaw has a relatively large pitch in the order of about 3.degree.. The spring loaded notch lever is provided with a single tooth which meshes with the outer toothing of the movable jaw, the tooth being arranged relatively close to the drag bearing of the notch lever. The thrust lever, which is also pressed against the outer toothing of the movable cutting jaw by a separate spring, has on its free end two teeth, which are arranged at a distance corresponding to the pitch. From the arrangement of the bearing between the two hand levers, the drag bearing of the thrust lever at the other hand lever, and the location of the meshing spot of the teeth of the thrust lever an initial knee lever angle in the order of 77.degree. results. This acute angle corresponds to the maximum opening position of the two hand levers. During the pressing together of the two hand levers towards each other the knee lever angle is continuously enlarged, where it has at first to be enlarged to a knee lever angle of approximately 90.degree. without any knee lever action. This happens under an unfavorable translation ratio. Compounding this is the fact that at a large opening angle between the two hand levers it is difficult and cumbersome to provide by hand the necessary force for moving the cutting jaws through the work piece. With work pieces of a corresponding diameter and/or of a material that is difficult to cut, the user of the scissors is forced to actuate the hand levers with both hands. This is not user friendly. In the second part of a single work step, in which the two hand levers are swung towards each other, not only the knee lever action is brought into effect, but the two hand levers are closer together anyway, so that they are more easily acted upon corresponding to the anatomic condition of the fingers on the hand. A final knee lever angle of approximately 115.degree. is attained, at which the knee lever drive provides a maximum translation.
With the known scissors a relatively large surplus travel is necessary. This surplus travel is understood to be the distance by which the movable cutting jaw has to be additionally swung towards the closing direction so that the tooth of the notch lever can mesh with the next tooth of the outer toothing of the movable cutting jaw. Due to the small radial distance between the drag bearing of the notch lever and the tooth of the notch lever this surplus travel is relatively large. It is furthermore disadvantageous that the thrust lever does not act purely tangentially but more radially on the outer toothing around the drag bearing of the movable cutting jaw, by which the corresponding leverage is reduced. The known scissors have disadvantages in their use that result from the interaction of the pitch of the outer toothing and the forming and geometric arrangement of the individual parts of the scissors.
On a further known cable cutter, which is constructed similarly, an outer toothing on the movable cutting jaw with a pitch of approximately 2.6.degree. is applied. The geometric arrangement is so that the notch lever, during the full travel of the hand levers towards each other, jumps over two teeth of the outer toothing, so that there is the advantageous possibility to swing the hand levers towards each other only for part of the swinging range, corresponding to the tooth of the notch lever jumping over just one tooth of the other toothing. A disadvantage is that the opening movement of the two hand levers towards each other is not limited, so that the user of such a cable cutter, if he wants to make use of the given advantage, has to stop the opening movement of the hand levers in time and reverse the direction of action of his manual force in order to make use of the advantageous travel. Whenever he does not carry out this manual limitation of the opening movement, the following actuation travel has to begin at a very large opening angle between the two hand levers, which here, too, is possible only by using both hands if the work piece is correspondingly shaped and fashioned.
From Putsch et. al., U.S. Pat. No. 5,218,768, a ratchet cutter is known, in which the drag bearing of the travel lever is disadvantageously removed from the outer toothing of the movable cutting jaw during the closing movement of the hand levers, so that the direction of the acting force becomes more unfavorable in the course of the closing movement. In the opened position the two hand levers enclose an angle that is so large that they can practically be taken only with two hands. In spite of a pitch of approximately 2.5.degree. on the outer toothing of the movable cutting jaw, a one-handed operation is not possible.